The troubling link between the invasive Japanese barberry and Lyme disease

By Eve Fox

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Bright red berries; thin, razor-sharp spines; woody stems; and small, round leaves of green or red. Japanese barberry is everywhere — in the plantings outside the post office, in the wild tangle of shrubs along the roadside, maybe even growing in your yard. Unfortunately, this popular ornamental is so aggressive that it’s crowding out native plants all along the East Coast, earning it a spot on the Plant Conservation Alliance’s “Least Wanted” list and getting it banned from sale in Canada.

Why is this plant so popular? “It’s a very pretty plant with lovely fall foliage that makes a nice contrast to the bright red berries,” says New Paltz-based gardening guru Lee Reich. “And it’s hardy: It can grow in sun or shade, and in rich soil or poor.” Which would be all well and good if Japanese barberry were not quite so successful at replicating itself. According to invasive species expert Jonathan Rosenthal of Kingston’s Ecological Research Institute, “the plant has tremendous powers to reproduce clonally by sprouting ‘daughter’ shrubs from its roots, from below-ground stems, and from places where its branches touch the ground.”

Perhaps more troubling is the fact that Japanese barberry bushes provide the perfect conditions for black-legged (deer) ticks, the primary vector for Lyme disease — one of the dreaded realities of life in our beautiful Valley. Recent studies have found that forests infested with Japanese barberry had 12 times more deer ticks than forests that were not infested. A glance at the New York Invasive Species Map confirms that woodlands from Long Island (where the sale of the plant is now banned) to Oneonta are rife with Japanese barberry and it appears to be heading northwards at a good clip.

On the plus side, researchers also have found that controlling the plant’s growth can cut tick populations by up to 80 percent. And right now is the perfect time to tackle this prickly dilemma, before the plants spread their seeds widely: Pull smaller plants up by hand, apply an herbicide, or hire a professional to use a propane torch to burn plants and roots — but be prepared to combine two or more of these methods to beat back this pesky plant.